Drawer construction

ABSTRACT

A drawer for an item of furniture. The drawer has a plastic molded subassembly of bottom wall, opposed sidewalls and rear wall. This subassembly is made from a self-skinning foam having longitudinal reinforcement in the form of ribs of increased skin thickness extending throughout the foamed core.

United States Patent Inventor Max E. Hosmer Charlevoix, Mich. App]. No. 853,404 Filed Aug. 27, 1969 Patented Oct. 5, 1971 Assignee Freedman Artcraft Engineering Corp.

Charlevoix, Mich.

DRAWER CONSTRUCTION 9 Claims, 4 Drawing Figs.

U.S. CI 312/330, 312/273 Int. Cl ..A47b88/100 Field of Search 312/330, 204, 294, 273; l8/DIG. 9, DIG. 13,5 BH, 5 P, 38, 17 H [56] References Cited! UNITED STATES PATENTS 3,112,969 12/1963 Gustafson et a1. 312/330 3,298,767 1/1967 Crandell et a1. 312/330 3,338,651 8/1967 Jacobson 312/330 X 3,462,208 8/1969 Black et a1 3l2/330X 3,312,516 4/1967 Krahn 312/330 Primary Examiner.lordan Franklin Assistant Examiner-Geo. V. Larkin Attorney-Wood, I-Ierron & Evans ABSTRACT: A drawer for an item of furniture. The drawer has a plastic molded subassembly of bottom wall, opposed sidewalls and rear wall. This subassembly is made from a self skinning foam having longitudinal reinforcement in the form of ribs of increased skin thickness extending throughout the foamed core.

PATENTEUUCT 51971 3610720 sum 1 BF 2 INVENTUR.

DRAWER CONSTRUCTION This invention relates to items of furniture and more particularly to a construction for a drawer of an item of furniture.

Nonmetallic furniture has always been manufactured with drawers made of wood. Periodically, consideration has been given to the idea of molding the drawers, but, because the cost of material was disproportionate to savings and advantages to be achieved with the molded construction, the idea was never commercialized. Consequently, fumiture manufacturers have stuck to their time-honored nailed, glued, or dovetailed wooden drawer construction.

While wooden drawers have traditionally been the best available, they have always been subject to criticism because of the tendency of wood to warp and change dimensions. Additionally, the most expensive wooden drawers often come apart after a prolonged time either because of an error in their manufacture or because of an inherent shortcoming of the material from which the drawers are manufactured. More recently, wooden drawers have become expensive because of the cost of materials and labor involved in their manufacture.

It has therefore been an objective of this invention to provide a new and improved drawer construction which is not subject to any or at least less subject to these criticisms. Specifically, it has been an objective of this invention to provide a drawer construction which is less expensive to manufacture than a wooden drawer of comparable size and strength.

Another objective of this invention has been to provide a new and improved drawer construction which is stable and not subject to warpage or dimensional changes.

These objectives are achieved and this invention is partially predicated upon the concept of manufacturing a molded drawer subassembly comprising sidewalls, bottom wall, and rear wall from a foamed plastic material which is self-skinning during the molding process and which is selectively reinforced or strengthened by varying thicknesses of skin over the surface of the drawer.

The drawer produced by this process has numerous advantages over conventional wooden drawers in addition to those enumerated above. Specifically, the freight weight of the drawer is less than that of a comparable size drawer manufactured of wood. It may be manufactured without any machining steps since screw holes or rivets may be molded directly into the subassembly. It has the advantage of having a nonpcrmeable hard rigid skin over the exterior which rigidifies and very effectively protects the drawer against damage. The skin may be made to simulate wood in appearance but may be made much smoother and thus much more friction free.

These and other objects and advantages of this invention will be more readily apparent from the following description of the drawings in which:

FIG. 1 is a front perspective view of a drawer incorporating the invention of this application,

FIG. 2 is a rear perspective view of the drawer of FIG. 1,

FIG. 3 is a cross-sectional view through the drawer taken on line 3-3 ofFIG. 2, and

FIG. 4 is a cross-sectional view through a mold in which the molded portion of the drawer is manufactured.

Referring to FIGS. 1 and 2 there is illustrated a complete drawer assembly incorporating the invention of this application. This drawer comprises a drawer front 11 secured to a molded plastic subassembly 12 by metal brackets 13 and 14. The molded subassembly 12 comprises a bottom wall 15, sidewalls 16 and 17 and a rear wall 18, all of which are a unitary molded assembly.

Runner grooves 33 extend longitudinally along the outside surface of each of the sidewalls I6 and 17. These grooves are adapted to receive a rigid runner or rollers of an item of furniture which guides the drawer in its movement within the fumi' ture slot or drawer receptacle.

The drawer front 11 may be manufactured from wood or plastic or a combination of these materials. It has a pair of headed rivets or screws 19 and 20 on each side. These screws are adapted to be received in keyhole slots 21 in the front lateral flanges 23 of the brackets 13 and 14 so as to secure the front 11 to the brackets. The brackets 13 and 14 are in turn secured to the sidewalls 16 and 17 of the molded subassembly 12 by rivets 22 which are molded into the sidewalls l6 and 17. In lieu of rivets, apertures may be molded into the walls and self-threading screws inserted into the apertures to pivotally connect the brackets 13 and 14 to the walls 16 and 17.

The subassembly 12 is a molded plastic article having a cellular or foam plastic core and a hard high-density integral solid skin or shell. It is produced from a gas expandable plastic material mixed with a blowing agent in a mold cavity. When the plastic material is mixed with the blowing agent, it causes the resulting mixture to expand and foam until the foam material completely fills the mold. Under proper pressure and temperature conditions, that part of the mixture of plastic material and blowing agent or melt" which contacts the surface of the mold forms a hardened shell of plastic material.

Various ones of many available gas expandable or foamable thermosetting or thermoplastic resins may be employed in the practice of this invention. Suitable resins include the thermoplastic casting materials such as nylon, polystyrene, polypropylene, and various ones of the vinyl family. Polyurethane polymers are particularly desirable materials for the practice of this invention. Such materials are disclosed in U.S. Pat. No. 3,443,007 of E. E. Hardy, issued May 6, 1969. Other patents which disclose suitable molding techniques and suitable compositions of both plastic resins and blowing agents for the practice of this invention may be found in Weissman et al.

U.S. Pat. No. 3,384,691, issued May 21, i968, and Hardwick U.S. Pat. No. 3,218,375, issued Nov. l6, I965.

One procedure which has been found to be particularly well suited to the application of this invention utilizes freon blown urethane foam and an isocyanate polyether catalyst system. The produced from this urethane foam has a rigid integral skin formed thereon during the molding process. This foaming product and catalyst system are well known and are commercially available from several commercial sources.

The molding process is carried on at a mold temperature of approximately l05 F. The internal pressures within the mold build to the range of 30 to 40 pounds per square inch. By vary ing the temperature of the mold surface, the thickness of the skin may be varied. Specifically, cooler sections of the mold cause the skin thickness to build or increase in the cooler area.

Referring to FIG. 3, there is shown a cross section taken on line 3-3 of FIG. 2. From this cross section, it will be seen that the low density porous core 25 is completely encased in a microporous dense skin 26. This skin varies in thickness from approximately 1/32 to is but is thickest or of increased crosssectional area at the comers 27, 28, 29 and 30 and along the top and bottom walls 31 and 32 of a runner groove 33. These comers or ribs act as reinforcement ribs to rigidify the drawer in a longitudinal direction. It is much denser, as for example, in the range of 30 pounds per cubic foot to 70 pounds per cubic foot than the porous core which has a density in the range of 0.5 pounds per cubic foot to 8 pounds per cubic foot. In the preferred embodiment in which. the subassembly is molded from urethane foam, the skin has a density of approximately 68 pounds per cubic foot and the porous density of approximately 7 pounds per cubic foot.

Referring to FIG. 4 there is illustrated the mold section in which the cross section illustrated in FIG. 3 is formed, As may be seen in this figure, the mold comprises an internal sidewall 35 and an interior bottom wall 36. The mold also has a sidewall 37 from which an upper flange 38 extends over to engage the top of the inner wall 35. A mold bottom wall 39 is also shown in this figure. Since the pressures involved in carry ing out this molding process are relatively low, i.e., 30 to 40 p.s.i., the mold may be made from any one of numerous materials capable of withstanding this pressure, as, for examcore has a ple, aluminum, steel, or any one of numerous plastics. The

outside wall 37 has a rib 40 formed interiorly of it and adapted to-generate the runners or groove 33 when the subassembly l2 is formed in the mold.

Adjacent each of the corners of the mold there is an aperture which extends through the mold walls 35, 37, and 39. These apertures 41, 42, 43, 44, 45, and 46 are adapted to carry liquid at a cooler temperature than the mold temperature throughout the mold so as to cause a buildup of skin 26 in the area of the aperture. Specifically, it will be seen that by lowering the temperature of the mold adjacent the apertures 42 and 43, the longitudinal ribs 28 and 27 of the subassembly are formed along the top corners of the drawer sidewalls. Similarly, the grooves 44 and 45 cause the temperature of the mold surfaces 49 and 50 to be lowered so that there is a buildup of skin adjacent the surfaces. This buildup results in areas 52 and 53 of increased skin thickness adjacent the surfaces 49 and 50. Similarly, the apertures 41 and 46 cause the corner surfaces 55 and 56 to be slightly cooler than the remainder of the mold so that there is a buildup of skin thickness in the areas of the comers 29 and 30.

Similar apertures throughout the mold carry cooling liquid parallel to the mold corners so that the vertical interior corners at the intersection of the sidewalls and the rear wall and at each horizontal comer structure of the rear wall are also caused to build up areas of increased skin thickness. Consequently, all comers of the subassembly 12 are of increased thickness similar to corners 27, 28, 29 and 30. Additionally, the increased thickness areas 52 and 53 adjacent the runner surfaces form longitudinally reinforcing ribs throughout the sidewalls of the drawer.

in lieu of utilizing cooling fluid in apertures of the mold to cool selected areas and particularly the comers of the mold, heating elements may be placed in the mold so as to cause the noncorner surfaces to be heated to a greater extent than the comers. The net result is the same in that the corner surfaces of the mold are cooler with the result that the skin formed over the porous core will be of increased thickness in the areas adjacent the cooler mold surfaces.

While I have described only a single preferred embodiment of my improved drawer construction, those persons skilled in the arts to which this invention pertains will readily appreciate numerous changes and modifications which may be made without departing from the spirit of my invention. Therefore I do not intend to be limited except by the scope of the appended claims.

Having described my invention I claim:

I. A drawer of an item of furniture comprising a bottom wall, a pair of opposed sidewalls, a rear wall, and a front wall,

each of said pair of sidewalls having a longitudinal runner groove extending inwardly from the outside surface thereof, said groove being adapted to receive a longitudinal runner of said item of furniture and to guide said drawer in its longitudinal movement over said runner,

at least said bottom wall, sidewalls, and rear wall being made from a self-skinning foam and being a unitary molded foam plastic structure, said foam plastic structure having a porous core and an integral hard surface skin, said skin being molded simultaneously with said core from the same chemical composition as said core but being of much greater density, tensile strength, compressive strength, and rigidity than the core, s'aid skin being impermeable and of varying thickness, said skin being of greatest thickness adjacent the corners of said walls and adjacent the top and bottom of said runner groove.

2. The drawer of claim 1, wherein said skin has a density in the range of 30 lb./cu.ft. to 70 lb./cu.ft. and said core has a density in the range of 0.5 lb./cu.ft. to 8 lb./cu.ft.

3. The drawer of claim 1, wherein said skin and core normally comprise a polyurethane polymer.

4. A drawer of an item of furniture comprising a bottom wall, a pair of opposed sidewalls, a rear wall, and a front wall,

at least said bottom wall, sidewalls, and rear wall being a unitary molded plastic structure, said structure having a porous core and an integral surface skin, said skin being formed simultaneously with said core from the same chemical composition as said core but being of much greater density, tensile strength, compressive strength, and rigidity than the core, and

multiple longitudinal supports,

at least said sidewalls being longitudinally reinforced by said supports of said skin which extend for the full length of said sidewalls, each of said ribs comprising a portion of said skin which is of greater thickness than the majority of said skin on said sidewall.

5. The drawer of claim 4, wherein said longitudinal supports are located at the comers of said sidewalls.

6. The drawer of claim 5, wherein additional longitudinal supports are located between the top and bottom comers of said sidewalls.

7. The drawer of claim 5, wherein said skin has a density in the range of 30 lb./cu.ft. to 70 lb./cu.ft. and said core has a density in the range of 0.5 lb./cu.ft. to 8 lb./cu.ft.

8. The drawer of claim 7, wherein said skin and core normally comprise a polyurethane polymer.

9. A drawer of an item of furniture comprising a bottom wall, a pair of opposed sidewalls, a rear wall, and a front wall,

at least said bottom wall, sidewalls, and rear wall being made from a self-skinning foam and being a unitary molded foam plastic structure, said foam plastic structure having a porous core and an integral hard surface skin, said skin being molded simultaneously with said core from the same chemical composition as said core but being of much greater density, tensile strength, compressive strength, and rigidity than the core, said skin being impermeable and of varying thickness, said skin being of greatest thickness adjacent the corners of said walls so that said increased thickness skin at the corners rigidities the drawer longitudinally of the drawer sidewalls.

UNI'IED s'izyrjmss PA'IENT' (mmcE CERTIFICNETE 0F CORRECTION Patent No. 3,610,720 Dated October 5, 1971 Inventofls) Max E. Hosmer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 34, after "The" and before "produced",

insert product Col. 2, line 49, after "1/32", insert inch and after "1/8" insert inch Signed and sealed this 28th day of March 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. A drawer of an item of furniture comprising a bottom wall, a pair of opposed sidewalls, a rear wall, and a front wall, each of said pair of sidewalls having a longitudinal runner groove extending inwardly from the outside surface thereof, said groove being adapted to receive a longitudinal runner of said item of furniture and to guide said drawer in its longitudinal movement over said runner, at least said bottom wall, sidewalls, and rear wall being made from a self-skinning foam and being a unitary molded foam plastic structure, said foam plastic structure having a porous core and an integral hard surface skin, said skin being molded simultaneously with said core from the same chemical composition as said core but being of much greater density, tensile strength, compressive strength, and rigidity than the core, said skin being impermeable and of varying thickness, said skin being of greatest thickness adjacent the corners of said walls and adjacent the top and bottom of said runner groove.
 2. The drawer of claim 1, wherein said skin has a density in the range of 30 lb./cu.ft. to 70 lb./cu.ft. and said core has a density in the range of 0.5 lb./cu.ft. to 8 lb./cu.ft.
 3. The drawer of claim 1, wherein said skin and core normally comprise a polyurethane polymer.
 4. A drawer of an item of furniture comprising a bottom wall, a pair of opposed sidewalls, a rear wall, and a front wall, at least said bottom wall, sidewalls, and rear wall being a unitary molded plastic structure, said structure having a porous core and an integral surface skin, said skin being formed simultaneously with said core from the same chemical composition as said core but being of much greater density, tensile strength, compressive strength, and rigidity than the core, and multiple longitudinal supports, at least said sidewalls being longitudinally reinforced by said supports of said skin which extend for the full length of said sidewalls, each of said ribs comprising a portion of said skin which is of greater thickness than the majority of said skin on said sidewall.
 5. The drawer of claim 4, wherein said longitudinal supports are located at the corners of said sidewalls.
 6. The drawer of claim 5, wherein additional longitudinal supports are located between the top and bottom corners of said sidewalls.
 7. The drawer of claim 5, wherein said skin has a density in the range of 30 lb./cu.ft. to 70 lb./cu.ft. and said core has a density in the range of 0.5 lb./cu.ft. to 8 lb./cu.ft.
 8. The drawer of claim 7, wherein said skin and core normally comprise a polyurethane polymer.
 9. A drawer of an item of furniture comprising a bottom wall, a pair of opposed sidewalls, a rear wall, and a front wall, at least said bottom wall, sidewalls, and rear wall being made from a self-skinning foam and being a unitary molded foam plastic structure, said foam plastic structure having a porous core and an integral hard surface skin, said skin being molded simultaneously with said core from the same chemical composition as said core but being of much greater density, tensile strength, compressive strength, and rigidity than the core, said skin being impermeable and of varying thickness, said skin being of greatest thickness adjacent the corners of said walls so that said increased thickness skin at the corners rigidifies the drawer longitudinally of the drawer sidewalls. 